Am I serious? For the most part, going forward he was muck. I counted numerous times balls were played to him a little short or long, and he never made the effort to reach them. If it wasn't within range it seemed like he wasn't bothered. Plus, there was at least 2 good attacks we went on and Diaby was hanging back in CM instead of charging up the wing, WHERE A WINGER IS SUPPOSED TO BE, on one occasion Cesc had to try and hold the ball up against half the Milan defense because, when he looked around Diaby was nowhere to be seen.
Oh, and not to mention the amount of times he went on runs and ran straight into a wall of Milan defenders, something he does ALL the time.
I don't totally blame him, he's a CM being asked to play on the wing, but he has a central players mentality, he's just not clued in enough to be an attacking player. Just because he scored some cracking goals doesn't mean he's Marc Overmars.
As I said, you don't play someone on the wing for their defensive play.